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Thunderbolt: Beyond USB and eSATA

When I started in computing, we had two main peripheral interface choices: RS-232 serial and Centronics parallel ports. Neither was fast. RS-232, which was the more generally useful of the pair, topped out in early days at 20 kilobits per second (kbps). That was then. This is now.

Today, <a href="http://www.itworld.com/hardware/98987/usb-30-vs-esata-is-faster-better">USB 3.0 can hit 625 MegaBytes per second (MBps) and eSATA can handle up to 300 MBps</a>. Intel's creation and Apple's newest darling interface technology, <a href="http://www.itworld.com/thunderbolt">Thunderbolt</a> can blast data along at 10 Gigabits per second (Gbps).

[ <a href="http://www.itworld.com/hardware/177335/apple-thunderbolt-test-results">Apple Thunderbolt test results</a> and <a href="http://www.itworld.com/storage/201457/even-more-thunderbolt-results">Even more Thunderbolt results</a> ]

That's great news! If, that is, you have a PC and operating system that supports Thunderbolt and peripherals that can work with it. There aren't many of any of these at the moment. Apple and Intel want that to change as fast as possible.

Indeed, one reason why <a href="http://www.itworld.com/networking/175889/usb-30-great-technology-hard-find">USB 3.0 has so slow off the mark</a> was because Intel still hasn't built in support for it in its motherboards. Thunderbolt, though, is already available on some hardware, and will include this new technology, along with USB 3.0, on its 2012 Ivy Bridge motherboard architecture. In the meantime, Apple is already <a href="http://www.itworld.com/hardware/141959/thunderbolt-macbook-pro-last-notebook-youll-ever-need">building Thunderbolt into its latest model MacBook Air, MacBook Pro</a>, iMac, and Mac mini computers.

[ Review: <a href="http://www.itworld.com/hardware/141959/thunderbolt-macbook-pro-last-notebook-youll-ever-need">Thunderbolt MacBook Pro: The last notebook you'll ever need</a> ]

So what does Thunderbolt bring to the table? Well, according to Apple, Thunderbolt isn't a replacement for USB 3.0, it's a complement to it. I'm not sure quite what they in mind when they say that, I think it may be more of a sop to USB-users who don't want to replace their hardware than a real plan for the future. Certainly, there's no need whatsoever to connect your keyboard or mouse to your computer with Thunderbolt!

What is Thunderbolt anyway?

Thunderbolt was first known as <a href="http://www.itworld.com/light-peak">Light Peak</a>. Intel gave it that name because it was meant to be a purely optical technology. By 2009, Intel realized that people like having peripherals that could be powered by the interface, ala USB, so they added support for a copper wire based system. With this, wired based Thunderbolt could transfer up to ten watts (10W) of power (USB 2.0 and 3.0 can only handle up to five watts).

Thunderbolt can still support optical only connections, but I expect only a handful of devices will ever support that use. That said, Thunderbolt, at heart, remains optically based. If you were to carefully tease apart a Thunderbolt transceiver, you'd find two tiny light Vertical Cavity Surface Emitting Lasers (VCSELs) and two tiny photo detectors. The lasers are the width of two human hairs placed side by side. They can transmit light over each of the two channels using fiber-optic cable 125 microns wide. The photo detectors receive the light from the other end, and circuitry within the Thunderbolt interface converts those to wired electrical signals.

Those two VCSELs and accompanying circuity enable Thunderbolt to send and receive up to 10Gbps at the same time. That's none too shabby!

Once those high-speed signals hit the transceiver, a controller switches the raw data into its two supported data transfer protocols: DisplayPort and PCI Express. That, in turn, means that it won't take peripheral makers of devices such as high-end monitors and external hard drives too long to add Thunderbolt compatibility to their hardware. In addition, since both data protocols can be run over a single Thunderbolt cable, one cable type and port can support almost any device using the interface.

Even before we see a new generation of Thunderbolt compatible devices show up though, you'll be able to use your older DisplayPort equipment with Thunderbolt. The cable and port are both DisplayPort compatible. It won't be as fast, of course, but you will be able to use your older hardware instead of having to upgrade.

Unlike the peripheral ports we've been using for the last few years, Thunderbolt also enables you to "daisy-chain" up to seven Thunderbolt-equipped devices from a single port. You can even, in theory, get full speed from all these devices in one chain.

Daisy-chaining sounds great doesn't it? It would to me too, except I remember back decades ago when SCSI (Small Computer System Interface) offered that same ability. And guess what? I could usually get SCSI chains to work one time in four. I'll believe Thunderbolt daisy-chains work with multiple devices from different vendors after I've managed to get it to work myself, and not a moment before then!

Even with that daisy-chain, Thunderbolt is designed to have extremely low latency. That is to say, there should be very little delay between when you or your devices issue a data-transfer command and you get the results. This means, Intel says, that Thunderbolt will work very well with professional audio and video applications. In particular, it is meant to work well with Intel's Quick Sync Video technology.

Thunderbolt speed

Is Thunderbolt really that fast? In <a href="http://www.computerworld.com/s/article/9218995/Apple_s_13_in._MacBook_Air_All_this_style_and_speed_too" target="new">tinkering with it on my new MacBook Air</a>, it sure felt faster than fast. What's far more telling is that in recent tests using an Apple MacBook Pro and the LaCie Little Big Disk external hard drive, the results were, as the testers put it: "<a href="http://www.itworld.com/hardware/177335/apple-thunderbolt-test-results">The results were incredible</a>. Using AJA System Test set to use 16GB of 4K frames (to really push it), the Little Big Disks delivered an average read speed of 835.5MBps and an average write speed of 353.1MBps -- faster than many fibre channel systems and equivalent to quite a few streams of uncompressed HD respectively."

While I'm not ready to replace a data center's fibre channel, SAN (storage area network) fabric with Thunderbolt, I'd be game to use it to directly connect workstations to the SAN rather than using Gigabit Ethernet. It's that fast.

As my fellow IT World author, <a href="http://www.itworld.com/personal-tech/138569/thunderbolt-hard-drives-should-make-data-transfer-scream">Kevin Fogarty put it</a>, "For once, I can't wait to replace the plugs on my current hardware with something that showed up first on a Mac." I agree. It really is impressive.

But you know what's even more impressive? Intel claims that future versions will be able to reach 100 Gbps. Can you say, "Vroom!"? I knew you could.

Thunderbolt devices and prices

The only real problem with all this Thunderbolt goodness is that we still don't have many shipping peripherals that support it. Here's the complete list so far, according to Apple:

- Apple Thunderbolt Display

- Promise Pegasus R4 and Pegasus R6 - LaCie Little Big Disk - Sonnet Fusion RAID

- Blackmagic UltraStudio 3D - Matrox MX02

- Promise SAN Link Fibre Channel adapter - Sonnet Allegro FireWire 800 adapter - Sonnet Presto Gigabit Ethernet adapter

That's not much. These devices, as you'd expect, aren't cheap. Just a <a href="http://9to5mac.com/2011/06/27/apple-about-to-roll-out-its-own-thunderbolt-cable-for-data-transfers-and-displays/">Thunderbird cable alone will run you $49</a>.

So should you buy into Thunderbird? Or just make do with USB and eSATA for now?

Much as I like it, for now, I think only people who are into creating high-end video content should bother with it. There's just not enough supported equipment and what is available comes with too high a price tag.

That said, if you are a professional or prosumer video creator, what are you waiting for? A high-end MacBook Pro with Thunderbird-equipped storage devices or Thunderbolt connection to your SAN is <em>exactly</em> what you need. With both Apple and Intel supporting Thunderbolt I see no reason for you to fear another Firewire debacle.

Thunderbolt will become a mainstream technology; there will be many Thunderbolt devices coming down the road and they'll eventually be at affordable prices. By this time next year everyone will realize this. Serious video creators might as well invest in it now though. Enjoy!


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